Preheat the oven to 325 F. Grease an 8 inch square baking pan OR line the pan with parchment paper or foil allowing a little overhang and spray with nonstick cooking spray for an easier clean up. Set aside.

Mix the melted butter and Oreo crumbs until thoroughly combined. Press the mixture into the bottom of the prepared pan. Bake in preheated oven for 6 minutes. Remove pan to a cooling rack.

While the crust is cooling, prepare the chocolate chip cookie dough. In a large bowl with an electric mixer (or use a stand mixer), beat butter, brown sugar, granulated sugar, salt and vanilla until smooth and thoroughly combined, about 1 minute. Mix in the flour on low speed, and mix until just incorporated. Mix in the chocolate chips. Set aside.

In the bowl of a stand mixer or in a large bowl cream together the cream cheese and sugar until smooth. Mix in the egg and vanilla on low speed just until combined. Add the 1/2 cup melted chocolate (that has been cooled slightly) and mix just until combined again. Pour the cheesecake batter into the prepared crust.

Flatten the clumps of dough in your palms to flatten them out a bit. Distribute the cookie dough onto the top of the cheesecake batter. Be sure to use all of the dough. You will cover most of the cheesecake batter.

Bake for about 30-32 minutes, until the top feels dry and firm (the cookie dough) and the entire pan looks set. Move bars to a cooling rack and allow to cool completely. After 30 minutes, I popped mine in the refrigerator.

Slice into desired size and store in the refrigerator. I serve these bars cold.